The intended victim of the alleged abduction and beheading plot was being guarded by police last night, along with several members of his immediate family.

He is a British Muslim in his 20s who has served in the British army for a number of years and has recently completed a tour of duty in Afghanistan. He is also thought to have connections with the Midlands, but it is unclear whether he is known to any of those being questioned last night.

The operation by the police and security services which culminated in yesterday's arrests had been under way for six months, suggesting the intended victim had been selected some time ago.

West Midlands police and the Ministry of Defence were refusing to talk about the young soldier or the perceived threat to his life yesterday; the police insisted that speculation about the nature of the plot was "potentially damaging to the investigation or any future court cases".

According to security sources, however, the plan had been to abduct the soldier, a lance corporal, and take him to a hideaway. There he was to be filmed pleading for his life in a manner reminiscent of the kidnapping of Ken Bigley, the 62-year-old engineer from Liverpool, and several other hostages seized in Iraq. The final film was, allegedly, to have shown the young soldier being beheaded.

The footage was to have been posted on the internet, bypassing traditional media which would have been reluctant to broadcast such material, the sources claimed.

There are 330 Muslims serving in the UK armed forces. Last month local newspapers in the Midlands reported that a recruitment drive intended to attract more Muslim recruits to the army had failed. Would-be recruits had been offered halal rations during activity days at a barracks at Nuneaton, and women were told that they could wear headscarves as part of their uniform. Only 15 people signed up.